So Help Me Codd

"The key, the whole key, and nothing but the key, sohelp me Codd." That's the mnemonic I still use to help me remember thedifference between the second and third normal forms of a normalized database(in second normal form, a nonkey column depends on the whole primary key; inthird normal form, it depends on nothing outside the primary key).

See also: Time Warp: What Is a Relational Database?

Edgar F. Codd, the father of the relational database model,died April 18, 2003, at the age of 79. Codd's groundbreaking work in the fieldof relational database management systems (RDBMSs) paved the way for what manyof us do professionally. Database administrators' and developers' lives wouldbe radically different today without Codd's work and the subsequentcommercialization of the relational model by major database vendors.

Working as an IBM researcher in 1970, Codd developed 12 rulesof database design that have become the guiding light for the design of allmodern relational databases. As SQL Server Magazine senior technical editorMichael Otey notes, "Although most databases don't conform to all 12 ofCodd's rules, the rules of database design that he conceived are as vital todayas they were when they were introduced, and their core concepts have sinceformed the basis of all of today's commercial relational databasesystems."

What was the database world like before the relational model?Most databases used network or hierarchical data models, which required you todefine relationships before executing queries. As we all know, SQL now lets usquery data in a more flexible manner and doesn't require us to define all ofour query paths in advance.

In his original paper, "A Relational Model of Data forLarge Shared Data Banks", Codd explained the significanceof his new model: "The relational view (or model) of data...appears to besuperior in several respects to the graph or network model presently in voguefor non-inferential systems. It provides a means of describing data with itsnatural structure only—that is, without superimposing any additional structurefor machine representation poses. Accordingly, it provides a basis for a highlevel data language which will yield maximal independence between programs onthe one hand and machine representation and organization of data on theother."

Of course, the relational model seems simple and obvioustoday, but Codd's model was anything but obvious at the time, and it paved theway for a $7 billion industry that's at the center of all business-basedcomputing today. This week, take a moment to honor the contributions of a giantin the world of database. If you haven't already done so, read Codd's originalpaper. You might be amazed at the innovation of a person who knew how to thinkoutside the box—before most of us even knew there was a box.

Learn more: When Not to Normalize Your Database